US3742474A - Flame detector - Google Patents

Flame detector Download PDF

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Publication number
US3742474A
US3742474A US00131898A US3742474DA US3742474A US 3742474 A US3742474 A US 3742474A US 00131898 A US00131898 A US 00131898A US 3742474D A US3742474D A US 3742474DA US 3742474 A US3742474 A US 3742474A
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Prior art keywords
flame
flame detector
detector according
circuit
amplitude
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US00131898A
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English (en)
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P Muller
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Cerberus AG
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Cerberus AG
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/12—Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Definitions

  • Fleld oiSearch' cludes a demodulator and filter, having a p range of 328/2 250/833 217 207 about 2'40 Hz to demodulate the signal, and a further detector circuit detecting randomly.
  • the FLAME DETECTOR Flame detectors have been proposed to automatically indicate the presence of flames, forexample to act as fire alarms, or to supervise control burning, for example in furnaces or the like.
  • the flame detectors usually include a photosensitive transducer, such as a photo cell, a photo diode, or a photo resistance which is located to be sensitive to the radiation emitted by the flame, for example within the infrared or ultraviolet spectral region, and to provide an electrical output signal.
  • a circuit is then connected to the photoelectric sensing element which is so arranged that an alarm signal, or a control signal is provided if a flame is present, or not present, in the path of radiation to the photo cell.
  • One known arrangement discriminates between radiation'from a flame and from spurious radiation by selecting the .higher proportion of infrared radiation which is present when flames arise due to a fire.
  • a redsensitive and blue-sensitive photo cell are provided, serially connected, and the electrical circuit is so arranged that an alarm signal is derived only when the red/blue ratio exceeds a predetermined value.
  • Flame detectors of this type can give erroneous alarms when strong infrared radiation is applied thereto. If, however, spurious radiation having a heavy blue content is applied, then no alarm is given regardless of the presence of a heavy infrared content in extreme cases, and in any I event, the sensitivity of the device to radiation from flames is substantially reduced.
  • the electrical circuit includes a frequency sensitive filter passing frequencies only within a certain predetermined range, for example 5-25 Hz or 2-40 Hz. Arrangements of this type may, however, be subject to spurious response by reflection from radiation occurring on movable or rotating parts having, by chance, a similar frequency of recurrence; or they may be activated by fluorescent lamps or other lamps which have flicker. It has been proposed to reduce spurious responses by making the flame sensitive element more responsive to radiation from a flame, for example by use of filters in the infrared region and responsive to the wave lengths most likely to arise due to flames, as well as by filters suppressing the wave lengths derived from the most usual interfering radiation sources. This, however, is a solution which is satisfactory only in a limited way, since frequently infrared radiation is reflected by moving, or rotating portions of equipment and machinery so that erroneous indications are also obtained.
  • the invention is based on the realization that the lowfrequency flicker from flames is not regular, or periodic.
  • a fire usually is characterized by flames which start as single tongues of fire from the source of the fire,
  • the sequence of these various light pulses is such that they will lie within the above-mentioned low-frequency range; neither their amplitude, nor their recurrence is regular, however.
  • the invention thussolves the problem of recognizing flames by distinguishing flame radiation from interfering radiation, in that the periodic, regularly recurring radiation within a preferred low-frequency range is separatedv from the nonperiodic, randomly recurring portion. An alarm is given only if the randomly recurring portion exceeds a certain predetermined threshold value.
  • the randomly recurring irregular portion of the signal can be separated from the regularly recurring periodic portion by amplitude demodulation or frequency demodulation; an aboslute value of the irregular, randomly recurring portion can be usedto effect alarm or control functions; or a relative value'can be used, that is, a signal in which the proportion of randomly recurring radiation to periodic radiation is utilized for alarm or control functions. Additionally, such porportions can be utilized to control the sensitivity of the transducer, or the circuit as a whole, asdesired.
  • FIG. 1 is a schematic block circuit of a flame detector in accordance with the present invention, with signals occurring in the various blocks indicated the'rebelow.
  • FIG. 2 is a schematic circuit diagram of a flame detector with amplitude demodulation;
  • FIG. 3 is a schematic circuit diagram of the amplitude demodulator with a separate spurious signal indication
  • FIG. 4 is a schematic circuit diagram of a frequency independent amplitude demodulator
  • FIG. '5 is a schematic circuit diagram for an amplitude demodulator having automatic gain control (AGC).
  • AGC automatic gain control
  • FIG. 6 is asch'ematic circuit diagram of a frequency demodulator.
  • a photoelectric sensing element 1 which is a photoelectric transducer providing an electrical output signal, of known construction, such as a photo cell, photo diode, photo resistance, photo transistor, or the like.
  • a red or infrared filter can be interposed in front of the sensing surface of sensor 1 to contribute to suppression of noise radiation.
  • More than one photoelectric sensing element can be used, the various sensors having different spectral sensitivity, and being arranged in series circuits, differential circuits, or the like. Spurious radiation of specific spectral composition can thus be suppressed, as known.
  • the output signal of the photosensitive element 1 includes an irregular mixture of various frequencies. It is applied to a frequency selective amplifier 2.
  • the frequency pass band of this amplifier 2 is so selected that only those frequencies-derived from a flame, which have the highest intensity and occur most frequently, are passed.
  • a frequency band pass of, for example, from -25 Hz or 2-40 Hz is suitable. Steady state portions of received radiation, as well as undulations of higher frequencies, such as line frequencies (50 or 60Hz) are not passed by amplifier 2. Interference by uniform light, for example reflections derived from rapidly rotating machine elements,'and apparatus driven by machinery, are thus filtered out and removed.
  • the subsequent circuit includes an a-c amplifier 5 and an integrator and threshold detector 6. Circuits 5 and 6 separate the alternating current component of the signal from the direct current component of the signal derived from filter 4 and then provide an alarm signal if the alternating current signal persists for a predetermined period of time. Alternating current amplifier 5 has a lower frequency cutoff which is substantially below the upper frequency limit of low-pass filter 4. Threshold detector and integrator 6 can operate in various ways, for example by forming the effective value of the output signal ofamplifier 5 by means of rectification, or use of half waves of one polarity, in order to provide pulses upon exceeding a certain threshold value, and count of the pulses within units of time, or by means of other known arrangements.
  • a flame detector with amplitude demodulation is illustrated in detail in FIG. 2.
  • a photo resistance 10 forms the photoelectric element 1.
  • Photo resistance 10 is connected in series through a resistance 18 between a pair of. d-c buses 30, 31.
  • the junction point between photo resistance 10 and .resistor 18 is connected over a condenser 13 to the base of a first transistor 11.
  • Resistances 24, 19 and 22 form the collector, emitter, and base resistors, respectively.
  • Condenser 16, connected between the collector of transistor 11 and bus 30 bypasses high frequencies and thus limits the highfrequency response.
  • the voltage drop across the collector resistance 24 is coupled by means of condenser 14 to the base of second transistor 12 having collector, emitter, and base resistances formed of resistors 20, 25 and 23 respectively.
  • Transistors 11. and 12 form a frequencyselective alternating current amplifier, having a lower frequency limit determined by the coupling condensers 13, 14 and 17 and an upper frequency limit determined by condensors 16 and 15.
  • the output signal of the second transistor 12 is coupled by means of condenser 17 and resistance 21 to the combined amplitude demodulator 3 and 4.
  • Diode 26 forms the input to the amplitude demodulator.
  • the output from diode 26 is connected to a parallel network formed of a condenser 27 and a resistance 28, forming a low-pass filter.
  • a condenser 27 and a resistance 28 forming a low-pass filter.
  • other known low-pass filter circuits having a steeper characteristic for their frequency pass band can be used.
  • the upper frequency limit of the low-pass filter mustbe so arranged that the frequencies applied thereto by amplifier 2 are absorbed, so that periodic oscillations with frequencies within the pass band of amplifier 2 provide, at the output of amplitude-demodulators 3 and 4, a direct current signal having as little ripple as possible.
  • the output signal from the amplitude demodulators 3 and 4 is applied over coupling condenser 29 to the base of a third transistor 32, having collector, emitter and base resistances 36, 37, 34 and 35, respectively.
  • This stage of the network operates as an alternating current amplifier having a lower frequency limit which is selected to be lower than the highest limit of the frequency band of the' amplitude demodulator.
  • the output of the transistor 32 thus will only reflect the nonperiodic, random flicker of flames providing a modulation signal to sensor 1.
  • This output signal is applied by coupling condenser 38 to the base of a further transistor 33 having collector and base resistances formed of resistors 41, 39, respectively.
  • a diode 40 is connected between the base and the positive bus 30, so that transistor 33 is conductive only during the negative half wavesof the modulation swing applied thereto, thus successively charging a condenser 43 over a resistance 42, so long as modulating oscillations of very low fre quencies are applied to transistor 33.
  • the base-emitter voltage of transistor 33 forms a threshold potential.
  • Zener diode 44 When the charge on condenser 43 exceeds the Zener voltage of Zener diode 44, connected between resistance 42 and the control electrode of a thyristor, such as a silicon controlled rectifier (SCR) 46, then Zener diode 44 becomes conductive to fire the SCR 46.
  • the I SCR has its anode-cathode path connected across the supply buses 30, 31.
  • the current supplied over the buses 30, 31 to the flame detector risessuddenly; this'increase in current can be detected by an alarm network, not shown, to provide an alarm or controller signal.
  • An overcurrent, or currentsensitive relay may serve as such an alarm or control element.
  • Resistance 45 connected to the gate electrode of SCR 46, is a holding and bypass resistor.
  • the flame detector in accordance with the circuit of FIG. 2 supplies an alarm signal only when the photo .resistance 2 is subjected to differences in light intensity within a certain low-frequency range and which have randomly occurring (in time) amplitude excursions.
  • a purely periodic undulation in light sensed by sensor 1 provides to the base of transistor 32 only a small input voltage, so that no alarm will be given.
  • FIG. 3 illustrates a circuit in which blocking of the flame detector by strong noise radiation, periodically recurring, is indicated. Strong periodic radiation will appear at the outputof the amplitude demodulator and be applied to a second threshold detector 7 (FIG. 3) which includes aZener diode 47 connected between the output of the amplitude demodulator and the control electrode of an SCR 49.
  • Zener diode 47 becomes conductive, SCR 49 fires and a separate signal line 50 supplies an additional control signal to I the alarm center.
  • a signal on line 50 will indicate that the flame detector is not in operative condition due to presence of masking strong periodic radiation.
  • FIG. 4 illustrates the circuit for another embodiment of an amplitude demodulator in which the pass band characteristics of the low-pass filter is in steps. This permits damping of the frequencies passed by amplifier 2 by a-predetermined value.
  • Diode S1 is again arranged at the input to circuits 3 and 4; the output of diode 51 is connected to a junction point which has a resistor 52 connected thereto, the other end of which is connected to bus 31; and an RC network formed of parallel connected resistor 53 and capacitor 55 connected to the junction.
  • a further condenser 54 is connected to the output of the RC network and to bus 31. Condenser 54 and resistance 53 determine the upper frequency limit. Condensor 55 lowers the impedance of the network for higher frequencies.
  • FIG. 5 illustrates a circuit in which overloading of the amplifier 2 by strong periodically recurring oscillations can be inhibited.
  • Photosensitive resistor 61 is connected only at its negative side to the negative bus 31.
  • the positive side of photosensitve resistor 61 is connected to a voltage divider formed of resistances 59,
  • transistor 56 is conductive.
  • the base of transistor 56 is controlled over a resistance 57 from the output of the amplitude demodulators 3 and 4. If the direct current voltage at the output of amplitude demodulator exceeds a certain voltage determined by the relative value of resistors 59, 60, and thus of the voltage at the junction point, that is at the emitter of treansistor 56, then the resistance of transistor 56 will-rise and thus the supply voltage to the photo resistance 61 will decrease. Amplifier 2 will thus be supplied at a lower input voltage preventing its overloading.
  • This automatic attenu ating circuit (which functions in the order of an automatic gain control circuit) thus prevents blocking of the amplifier even by strong periodically occurring light pusles and still provides sufficient sensitivity for radiation derived from flames, even in the presence of high level periodically recurring radiation, although the sensitivity to flames is somewhat reduced.
  • FIG. 6 illustrates a circuit utilizing a frequency demodulator 9 instead of v the rectifier-low-pass filter combination 3, 4, forming the amplitude demodulator.
  • the output signals of the alternating current amplifier 2 are applied to frequency demodulator 9, which includes a resistor 63, and a series network of apair of oppositely poled Zener diodes 66 and 67, to convert the output signals to square wave pulses.
  • the frequency demodulation is then carried out on the flank of the signal being applied to a band pass filter formed of resistance 64 and condenser 65.
  • the signal appearing at the output will have an amplitude which depends on the time the signal passes through zero, or null, and which can be further processed, as above described, in amplifier 5 and threshold detector 6.
  • the side slope, that is the flank of the frequency characteristic of the low-pass filter is to be so selected that the center of the band pass characteristic is somewhat in the middle of the median pass frequency of amplfiier 2.
  • the invention is not limited to detection by amplitude or frequency demodulation; any other system which permits separation, from a mixture of signals, of that portion which is irregular, and non-periodic, from other portions which are regular, periodic, can equally well serve to provide reliable indication of flames and thus provide a flame detector which is not subject to error indications and false alarms.
  • the combination of rectifier 3 and filter 4, forming an amplitude demodulator, or of the frequency demodulator 9 may thus, broadly, be termed a discriminator which discriminates between regularly recurring components and randomly recurring components of applied signals.
  • the present invention has been illustrated and dcscribed in detail in combination with a flame detector to give a signal when a flame is detected; the circuit may, of course, be used in the converse, that is to indicate that a flame is absent, or extinguished (for example when a furnace flameis to be sensed).
  • the control function for example due to firing of the SCR 46 may be obtained in various ways, as well known in the art, for example by separate control of the SCR 46, by control of a separate circuit or the like; or by triggering other relay or other (for example solid state) devices to carry out suitable indicator, alarm, or control functions as desired.
  • a signal derived at the output of Zener diode 44 can be applied to a control electrode of a switching transistor which, upon presence of the signal, is in non-conductive condition, and having its emittercollector path connected similarly to the anodecathode path of SCR 46. Upon absence of a flame, for
  • Flame detector having photo-sensitive transducer means responsive to flame radiation, and an electrical recognition circuit connected to said transducer means, deriving its input signal therefrom, and producing an output signal representative of presence, or absence of a flame, said circuit comprising means discriminating between regularly, periodically recurring components 'and randomly, nonperiodically occurring components of the input signal applied to said recognition circuit by said transducer comprising an amplitude detector providing an output representative of amplitude variations occurring in the output signal;
  • said circuit providing said output signal when the predetermined low-frequency range, randomly occurring components exceed a pre-set value.
  • Flame detector according to claim 6, including an RC network and a parallel resistance-capacity network connected, in parallel, to said RC network.
  • the electrical recognition circuit comprises an integrator and a threshold detector connected to said amplitude detector.
  • said amplitude demodulator includes a rectifier to provide an output signal therefrom which has a d-c and an a-c component;
  • said circuit further comprises means sensing the level of said d-c component and indicating when said d-c level exceeds a predetermined value.
  • Flame detector according to claim 1 including power supply means for said transducer; and means controlling the power applied to said transducer as a function of the output signal.
  • said power supply control means comprises a transistor having said transducer connected in circuit with the emitter-collector path of the transistor; 4
  • the frequency discriminator comprises a square wave pulse generating circuit and a circuit responsive to the flanks of the square wave pulses.
  • Flame detector according to claim 14, wherein the square wave pulse generating circuit comprises a plitude detector repsresentative of randomly occurring low-frequency components persist beyond a predetermined duration.
  • said integrator and threshold detector includes a condenser; said rectifler being connected to charge said condenser with half waves of one polarity;
  • the threshold detector includes a thyristor controlled by the charge on said condenser
  • Flame detector having photosensitive transducer means responsive to flame radiation, and an electrical recognition circuit connected to said transducer means deriving its input signal therefrom and producing an output signal representative of the presence, or absence of a flame, said circuit comprising means discriminating between regularly periodically recurring components and randomly nonperiodically occurring components of the input signal applied to said recognition circuit by said transducer comprising of the bandpass filter.
  • Flame detector according to claim 20, wherein the electrical recognition circuit comprises an integrator and a threshold detector connected to said amplitude detector.
  • the amplitude demodulator includes a rectifier to provide an output signal therefrom which has a d-c and an a-c component;
  • said circuit further comprises means sensing the level of said d-c component and indicating when said d-c level exceeds a-predetermined value.

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  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Control Of Combustion (AREA)
US00131898A 1971-03-04 1971-04-07 Flame detector Expired - Lifetime US3742474A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH324871A CH519761A (de) 1971-03-04 1971-03-04 Flammen-Detektor

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US3742474A true US3742474A (en) 1973-06-26

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US00131898A Expired - Lifetime US3742474A (en) 1971-03-04 1971-04-07 Flame detector

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US (1) US3742474A (enExample)
JP (1) JPS559613B1 (enExample)
BE (1) BE765881A (enExample)
CH (1) CH519761A (enExample)
DE (1) DE2204718C3 (enExample)
FR (1) FR2128329B1 (enExample)
GB (1) GB1377683A (enExample)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3852729A (en) * 1973-03-06 1974-12-03 Electronics Corp America Flame failure controls
DE2451449A1 (de) * 1973-12-14 1975-06-19 Forney International Dynamischer infrarot-flammendetektor
US3936648A (en) * 1973-03-20 1976-02-03 Electricite De France Flame monitoring apparatus
US3947218A (en) * 1975-01-23 1976-03-30 Honeywell Inc. Safety circuit for monitoring a flickering flame
US4220857A (en) * 1978-11-01 1980-09-02 Systron-Donner Corporation Optical flame and explosion detection system and method
US4249168A (en) * 1978-04-25 1981-02-03 Cerberus Ag Flame detector
US4464049A (en) * 1982-01-07 1984-08-07 Westinghouse Electric Corp. Illumination flicker meter
WO1985001140A1 (en) * 1983-09-06 1985-03-14 Firetek Corporation Optical fire or explosion detection system and method
US4533834A (en) * 1982-12-02 1985-08-06 The United States Of America As Represented By The Secretary Of The Army Optical fire detection system responsive to spectral content and flicker frequency
WO1987001230A1 (en) * 1985-08-22 1987-02-26 Santa Barbara Research Center Fire sensor statistical discriminator
FR2592976A1 (fr) * 1986-01-10 1987-07-17 Thomson Csf Dispositif de detection rapide d'incendie
EP0338218A1 (de) * 1988-03-30 1989-10-25 Cerberus Ag Verfahren zur Brandfrüherkennung
US4904986A (en) * 1989-01-04 1990-02-27 Honeywell Inc. IR flame amplifier
US5245196A (en) * 1991-08-29 1993-09-14 Hydrotech Chemical Corporation Infrared flame sensor responsive to infrared radiation
US6278374B1 (en) 2000-05-05 2001-08-21 Kellogg Brown & Root, Inc. Flame detection apparatus and method
US20040178914A1 (en) * 2003-03-11 2004-09-16 International Thermal Investments Ltd. Flame sensor and method of using same
US20140353473A1 (en) * 2013-05-31 2014-12-04 General Electric Company System and method for determination of flames in a harsh environment
US9251683B2 (en) 2011-09-16 2016-02-02 Honeywell International Inc. Flame detector using a light guide for optical sensing
US9780743B2 (en) 2015-10-22 2017-10-03 Google Inc. Light sensor readout system and method of converting light into electrical signals

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DE2741789C1 (de) * 1977-09-16 1987-02-19 Zeiss Carl Fa Verfahren und Vorrichtung zur Entdeckung von Hubschraubern
GB2129639B (en) * 1979-10-19 1984-10-31 France Etat Detecting vehicles
DE3318974C2 (de) * 1983-05-25 1985-10-17 Preussag AG Bauwesen, 3005 Hemmingen Flammenmelder
JPS61178621A (ja) * 1985-02-04 1986-08-11 Hochiki Corp 炎検出装置
JPH0278610A (ja) * 1988-09-13 1990-03-19 Yukiko Hiyougo 金属製身飾品の皮膚炎予防用塗布剤
NO180737C (no) * 1988-10-12 1997-06-04 Detector Electronics Apparat og fremgangsmåte for å diskriminere mellom elektromagnetisk stråling fra en brannkilde og fra en ikke-brannkilde
GB2223844A (en) * 1988-10-12 1990-04-18 Graviner Ltd Flame detector
US5237512A (en) * 1988-12-02 1993-08-17 Detector Electronics Corporation Signal recognition and classification for identifying a fire
EP0479009B1 (de) * 1990-10-05 1996-11-27 Siemens Aktiengesellschaft Wärmesensor
CN119559740A (zh) * 2025-01-23 2025-03-04 贵州电子科技职业学院 一种基于物联网的消防安全预警系统

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US2994859A (en) * 1956-06-15 1961-08-01 Specialties Dev Corp Flame detecting apparatus
US3156908A (en) * 1961-12-04 1964-11-10 Viking Corp Flame responsive apparatus
US3344277A (en) * 1965-02-23 1967-09-26 Kent F Smith Radiation monitor with background compensation
US3487222A (en) * 1967-11-03 1969-12-30 Bausch & Lomb Automatic gain control for self-calibrating a detection system
US3514209A (en) * 1968-02-09 1970-05-26 Du Pont Device for measuring the maximum intensity of a pulse of energy
US3531692A (en) * 1969-03-03 1970-09-29 Combustion Eng Activity detector having increased accuracy of response

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US2722677A (en) * 1954-08-31 1955-11-01 Electronics Corp America Fire detection apparatus
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US2981939A (en) * 1956-11-27 1961-04-25 Petcar Res Corp Fire detector system
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US2811711A (en) * 1951-05-19 1957-10-29 Electronics Corp America Fire method and apparatus
US2994859A (en) * 1956-06-15 1961-08-01 Specialties Dev Corp Flame detecting apparatus
US3156908A (en) * 1961-12-04 1964-11-10 Viking Corp Flame responsive apparatus
US3344277A (en) * 1965-02-23 1967-09-26 Kent F Smith Radiation monitor with background compensation
US3487222A (en) * 1967-11-03 1969-12-30 Bausch & Lomb Automatic gain control for self-calibrating a detection system
US3514209A (en) * 1968-02-09 1970-05-26 Du Pont Device for measuring the maximum intensity of a pulse of energy
US3531692A (en) * 1969-03-03 1970-09-29 Combustion Eng Activity detector having increased accuracy of response

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3852729A (en) * 1973-03-06 1974-12-03 Electronics Corp America Flame failure controls
US3936648A (en) * 1973-03-20 1976-02-03 Electricite De France Flame monitoring apparatus
DE2451449A1 (de) * 1973-12-14 1975-06-19 Forney International Dynamischer infrarot-flammendetektor
US3947218A (en) * 1975-01-23 1976-03-30 Honeywell Inc. Safety circuit for monitoring a flickering flame
US4249168A (en) * 1978-04-25 1981-02-03 Cerberus Ag Flame detector
US4220857A (en) * 1978-11-01 1980-09-02 Systron-Donner Corporation Optical flame and explosion detection system and method
US4464049A (en) * 1982-01-07 1984-08-07 Westinghouse Electric Corp. Illumination flicker meter
US4533834A (en) * 1982-12-02 1985-08-06 The United States Of America As Represented By The Secretary Of The Army Optical fire detection system responsive to spectral content and flicker frequency
WO1985001140A1 (en) * 1983-09-06 1985-03-14 Firetek Corporation Optical fire or explosion detection system and method
US4553031A (en) * 1983-09-06 1985-11-12 Firetek Corporation Optical fire or explosion detection system and method
WO1987001230A1 (en) * 1985-08-22 1987-02-26 Santa Barbara Research Center Fire sensor statistical discriminator
AU570594B2 (en) * 1985-08-22 1988-03-17 Kidde Technologies, Inc. Fire sensor statiscal discriminator
EP0234961A1 (fr) * 1986-01-10 1987-09-02 Kidde Dexaero Dispositif de détection rapide d'incendie
FR2592976A1 (fr) * 1986-01-10 1987-07-17 Thomson Csf Dispositif de detection rapide d'incendie
US4861998A (en) * 1986-01-10 1989-08-29 Thomson-Csf Rapid fire-detection device for armored vehicles
EP0338218A1 (de) * 1988-03-30 1989-10-25 Cerberus Ag Verfahren zur Brandfrüherkennung
US5005003A (en) * 1988-03-30 1991-04-02 Cerberus Ag Method of detecting fire in an early stage
US4904986A (en) * 1989-01-04 1990-02-27 Honeywell Inc. IR flame amplifier
US5245196A (en) * 1991-08-29 1993-09-14 Hydrotech Chemical Corporation Infrared flame sensor responsive to infrared radiation
US6278374B1 (en) 2000-05-05 2001-08-21 Kellogg Brown & Root, Inc. Flame detection apparatus and method
US20040178914A1 (en) * 2003-03-11 2004-09-16 International Thermal Investments Ltd. Flame sensor and method of using same
US9251683B2 (en) 2011-09-16 2016-02-02 Honeywell International Inc. Flame detector using a light guide for optical sensing
US20140353473A1 (en) * 2013-05-31 2014-12-04 General Electric Company System and method for determination of flames in a harsh environment
CN104215327A (zh) * 2013-05-31 2014-12-17 通用电气公司 用于在恶劣环境中确定火焰的系统和方法
US9780743B2 (en) 2015-10-22 2017-10-03 Google Inc. Light sensor readout system and method of converting light into electrical signals
US10320347B2 (en) 2015-10-22 2019-06-11 Google Llc Light sensor readout system and method of converting light into electrical signals

Also Published As

Publication number Publication date
GB1377683A (en) 1974-12-18
FR2128329A1 (enExample) 1972-10-20
DE2204718A1 (de) 1972-09-14
FR2128329B1 (enExample) 1977-04-01
BE765881A (fr) 1971-09-16
CH519761A (de) 1972-02-29
DE2204718C3 (de) 1985-05-30
JPS559613B1 (enExample) 1980-03-11
DE2204718B2 (de) 1978-08-31

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